JPH10289421A - Production of magneto-resistive multilayered films - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent heat treatment from deteriorating the soft magnetic characteristics of a free layer by laminating spin valve films in order of a ground surface layer, an antiferromagnetic layer consisting of a material of an NiMn type, a p-i-n layer, a nonmagnetic layer, the free layer and a protective layer in this order, successively from a substrate side, thereby producing magneto-resistive multilayered films. SOLUTION: The production of the magneto-resistive mutilayered films consists in depositing the ground surface layer 15 and the antiferromagnetic layer 11 of the NiMn type on the substrate and laminating the ferromagnetic layer which is the p-i-n layer 12 and the protective layer 16 thereon. Next, the layers are subjected to the heat-treatment while a magnetic field is impressed in a desired direction. The entire part of the protective layer 16 and part of the p-i-n layer 12 are then removed by ion trimming, etc. The p-i-n layer 12 is added thereon and the nonmagnetic layer 13, the free layer 14 and the protective layer 16 are laminated in this order. The ferromagnetic layer 12 is not completely removed but part of the ferromagnetic layer 12 is removed to remain to the extent of not exposing the antiferromagnetic layer 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetoresistive element used in a magnetic sensing portion such as a magnetic head or a magnetic sensor, and more particularly to an exchange coupling magnetic field acting between a ferromagnetic layer and an antiferromagnetic layer. The present invention relates to a method for manufacturing a magnetoresistive multilayer film using the same.

[0002]

2. Description of the Related Art With the increase in recording density of magnetic recording / reproducing devices represented by hard disk devices, recording bits, which are units for recording information, have been miniaturized more and more. For this reason, in the conventional inductive magnetic head which converts a change in magnetic flux into an electric signal, the signal output is reduced, and it becomes more difficult to reproduce information. Therefore, a recording / reproducing separated magnetic head capable of exhibiting higher sensitivity during reproduction has been proposed.

FIG. 8 shows a configuration of a recording / reproducing separation type magnetic head. The recording head including the upper shield film 24, the upper magnetic pole 26, and the coil 25 has an induction type mechanism in which a magnetic field is generated at the tip of the magnetic pole by passing a current through the coil 25 as in the related art. The reproducing portion including the bottom shield film 22, the upper shield film 24, the magnetoresistive film (MR film) 21, and the electrode 23 uses a magnetoresistive material showing a change in electric resistance with respect to an external magnetic field as a magnetosensitive portion.
A change in the magnetic field leaking from the recording bit is output as a change in voltage caused by a change in electric resistance. The playback signal is N
A pair of electrodes 23 are attached to both ends of an MR film 21 made of an i-Fe alloy or the like, and a constant current is applied to the signal film. , For reproducing a recorded signal. A reproducing head of this type is called a magnetoresistive head (MR head) because an MR film is used for the magnetic sensing element.

In order to obtain a high reproduction output with an MR head, a material exhibiting a large magnetoresistance effect is required.
A Ni—Fe alloy film having a resistance change rate of about% has been conventionally used as an MR film. However, since the giant magnetoresistance effect was discovered in a multilayer film in which a ferromagnetic layer and a nonmagnetic layer were stacked, a magnetoresistance effect multilayer film having a resistance change rate higher than that of a Ni—Fe alloy film has been applied to a reproducing head. It has become

FIG. 9 shows a cross section of a multilayer film showing a giant magnetoresistive effect disclosed in Japanese Patent Application Laid-Open No. 4-358310. This magnetoresistive multilayer film is also called a spin valve film. This multilayer film is composed of two upper and lower ferromagnetic layers separated by a nonmagnetic layer 13, that is, a free layer 14 and a pinned layer 12.
And the antiferromagnetic layer 11 laminated on the pinned layer 12. Since the magnetization of the pinned layer 12 exchange-couples with the magnetic moment of the adjacent antiferromagnetic layer 11, an apparent magnetic field called an exchange coupling magnetic field is applied. As a result, the magnetization direction of the pinned layer 12 is fixed to the direction of the exchange coupling magnetic field. On the other hand, the magnetization direction of the free layer 14 can freely change with respect to the signal magnetic field from the recording medium. Since the magnetization direction of the free layer 14 changes in response to the signal magnetic field, the magnetization directions of the pinned layer 12 and the free layer 14 change between parallel and antiparallel. The electrical resistance of the spin valve film is higher when the magnetizations of the pinned layers 12 and 14 are arranged antiparallel than when the magnetizations are arranged parallel. At this time, the resistance change rate of the spin valve film is 4 to 8
%, Which is higher than that of the Ni—Fe alloy film.

The material used for each layer of the spin valve film is selected so as to satisfy the characteristics required for each layer. That is, the free layer 14 is made of Ni-
An Fe alloy or a Co-based amorphous alloy is used, the nonmagnetic layer 13 is made of Cu having a small electric resistance, and the pinned layer 12 is made of Co or a Co—Fe alloy having a large magnetoresistance effect. For the antiferromagnetic layer 11, a material capable of generating a high exchange coupling magnetic field must be used in order to firmly fix the magnetization direction of the pinned layer 12.
Therefore, various antiferromagnetic materials have been studied so far in search of a higher exchange coupling magnetic field. They are roughly classified into three types: FeMn type, NiO type and NiMn type.
Can be classified into types.

[0007] The FeMn type antiferromagnetic material is an irregular alloy having an fcc crystal structure, and can easily obtain an exchange coupling magnetic field in a film-formed state (without the need for heat treatment). The direction of the exchange coupling magnetic field is parallel to the direction of the magnetic field applied to the substrate during film formation. Further, there is an advantage that an exchange coupling magnetic field can be obtained even if the antiferromagnetic layer is thinned to about 5 nm. However, on the other hand, the magnitude of the exchange coupling magnetic field is not sufficient,
Further, there is a major drawback that the corrosion resistance is poor and the head is corroded during the manufacturing process. MnIr, MnRh, etc. are classified into this type.

An exchange coupling magnetic field can be obtained in a NiO type antiferromagnetic material in a film-formed state. The direction of the exchange coupling magnetic field is parallel to the direction of the magnetic field applied to the substrate during film formation. Furthermore, since it is an insulator, there is an advantage that a so-called shunt loss is eliminated and a high resistance change rate can be obtained. However, since the exchange coupling magnetic field is small and the heat resistance is inferior, there is a disadvantage in that once heat is applied in the head manufacturing process, the film structure changes and the exchange coupling magnetic field disappears. CoO or a laminated film of CoO and NiO is classified into this type.

The NiMn type antiferromagnetic material is an ordered alloy having a fct structure (CuAuI type). In order to obtain this antiferromagnetic ordered alloy, heat treatment in a magnetic field is required after film formation. The direction of the exchange coupling magnetic field is parallel to the direction of the magnetic field applied during the heat treatment. The exchange coupling magnetic field of the NiMn type is much larger than the above two types of antiferromagnetic materials, and has the advantage of being less likely to be corroded in the head manufacturing process because of its excellent corrosion resistance.
The blocking temperature (temperature at which the exchange coupling magnetic field disappears) is higher than those of the above two types of antiferromagnetic materials, and the heat resistance is good. However, in the arrangement of each layer shown in FIG. 9, since the multilayer portion of the free layer / nonmagnetic layer / pinned layer is damaged by the heat treatment for forming the ordered alloy, the resistance change of about 4% is low as a spin valve film. There is a disadvantage that only the rate can be obtained. Pd5 besides Ni50Mn50 alloy
0Mn50, Pt50Mn50 and the like are classified into this type. In the present invention, this alloy is referred to as a Mn-X alloy (X is Ni,
Pd and Pt). The present invention particularly relates to a magnetoresistive multilayer film using a Mn-X alloy as an antiferromagnetic layer which requires a heat treatment after the film formation, and is capable of performing a heat treatment while maintaining a high resistance change rate and low noise. It is about the method.

[0010]

When a Mn-X alloy capable of generating a high exchange coupling magnetic field and having excellent corrosion resistance is used as an antiferromagnetic material, the conventional structure shown in FIG. The multilayer portion of the layer / nonmagnetic layer / free layer is damaged, and the rate of change in resistance is reduced and noise is increased, which is not preferable.

[0011] The ordering of the Mn-X alloy also depends on the thickness of the Mn-X alloy layer. When compared under the same heat treatment conditions, the thinner the Mn-X alloy layer, the more difficult it is to order and the smaller the exchange coupling magnetic field. Long-term heat treatment at a high temperature is required to sufficiently form a thin Mn-X alloy layer into an ordered alloy. However, as described above, the multilayer portion is seriously damaged and no magnetoresistance effect is exhibited. Therefore, in order to keep the heat treatment temperature low and obtain a sufficient exchange coupling magnetic field with the Mn-X alloy, the thickness of this layer had to be increased to about 30 nm. Mn with large rate of change in electrical resistance
When the -X alloy occupies half or more of the thickness of the spin valve film, there is a problem that the electric resistance of the entire spin valve film increases, which eventually causes a reduction in the resistance change rate.

Furthermore, in a spin valve film, it is necessary to make the direction of the exchange coupling magnetic field perpendicular to the direction of the easy axis of the free layer in order to obtain the linearity of the output. For this reason, Mn-
When an X alloy is used for the antiferromagnetic layer, the heat treatment must be performed while applying an external magnetic field in a direction perpendicular to the easy axis of the free layer. As a result of the easy axis of the free layer being rotated by the heat treatment in the magnetic field, there is a problem that the coercive force of the free layer is increased. All of these problems were associated with the heat treatment of the antiferromagnetic layer.

As shown in FIG. 10, an underlayer 15 is first provided on a substrate, and then an antiferromagnetic layer 11, a pinned layer 12, a nonmagnetic layer 13, a free layer 14, and a protective layer 16 are provided. Are stacked in this order. In this configuration, heat treatment can be performed first after the underlayer 15 and the antiferromagnetic layer 11 are formed. After the heat treatment, the degraded layer on the surface of the antiferromagnetic layer 11 is removed by ion milling or the like. The portion above the layer 12 is laminated on the antiferromagnetic layer 11. By doing so, heat is not applied to the pinned layer 12 and the free layer 14, so that it is expected that there is no deterioration in magnetic properties.

However, the inventor examined that the antiferromagnetic layer 11 having the configuration shown in FIG. 10 was subjected to a heat treatment, and then the pinned layer 12 and the nonmagnetic layer 13 were stacked in this order. On the contrary, the resistance change rate did not improve and the noise was not reduced. This is because the exchange coupling between the pinned layer 12 and the antiferromagnetic layer 11 was weak, and a sufficient exchange coupling magnetic field could not be obtained. Therefore, in the present invention, in the spin-valve film using the NiMn type antiferromagnetic layer in the laminated configuration in the order of FIG. 1, it is assumed that the heat treatment does not deteriorate the resistance change rate and the soft magnetic characteristics of the free layer. It is to provide a simple means.

[0015]

As shown in FIG. 2, a spin-valve film is formed by depositing an underlayer 15, an antiferromagnetic layer 11 made of a NiMn type material, a pinned layer 12, a nonmagnetic layer 13, The structure is such that the free layer 14 and the protective layer 16 are laminated in this order. This spin valve film is manufactured by the method shown in FIG. That is, Step 1. An underlayer 15 and a NiMn type antiferromagnetic layer 11 are formed on a substrate, and a ferromagnetic layer serving as a pinned layer 12 and a protective layer 16 are stacked thereon. Step 2. Heat treatment is performed while applying a magnetic field in a desired direction. Step 3. The entire protective layer 16 and a part of the pinned layer 12 are removed by ion milling or the like. Step 4. A pinned layer 12 is added on top of the non-magnetic layer 1.
3, the free layer 14 and the protective layer 16 are laminated in this order.

The point that such a method differs from the conventional method is that the ferromagnetic layer 12 is not removed entirely, but is partially left so that the antiferromagnetic layer 11 is not exposed. Examples will be described below in detail.

(Example 1) A spin valve film having the structure shown in FIG. 2 was produced by the following method. Step 1. S using a dual ion beam sputtering system
On a single crystal substrate, Ta (5 nm) / NiMn (20 n
m) / Co (3 nm) / Ta (3 nm). The number in parentheses is the thickness of each layer. The Ta layer on the Si single crystal substrate side was provided as a base film for improving the crystallinity of the entire laminated film, and the Ta layer on the top was provided as a protective film for protecting the laminated film from oxidation during heat treatment. The film formation conditions for each layer were all ion gun acceleration voltage 500
V, Ar gas pressure 6.0 × 10 −2 Pa, ion current 6 m
A, the substrate applied magnetic field is 8 kA / m. The ultimate pressure in the chamber is 2 × 10 −5 Pa or less. It was separately confirmed that the film composition of NiMn was Ni51Mn49 (at%). Step 2. Using a vacuum heat treatment furnace, the laminated film produced in step 1 was subjected to heat treatment in a magnetic field at 300 ° C. for 6 hours in a vacuum of 1 × 10 −3 Pa or less. The strength of the magnetic field applied during the heat treatment is 40 kA / m. After the heat treatment, the magnetization curve of this laminated film was measured with a VSM to confirm that an exchange coupling magnetic field of 32 kA / m was generated. Step 3. The laminated film is set in the dual ion beam sputtering apparatus again, and T
a All of the protective layer and the 1.5 nm Co layer were removed by ion milling. Milling conditions are a sub ion gun acceleration voltage of 300 V, an Ar gas pressure of 6.0 × 10 −2 Pa, and an ion current of 0.6 mA. By this process, the laminated film is in a state where a Co layer having a thickness of 1.5 nm is left on the NiMn layer. Step 4. Co (1.5 nm) / C is deposited on the laminated film without breaking the vacuum (that is, without exposing the laminated film to the atmosphere).
u (2 nm) / Co (1 nm) / Ni80Fe20 (5
nm) / Ta (5 nm). The film forming conditions are the same as in step 1. However, when the first Co layer is formed, the direction of the magnetic field applied to the substrate is made parallel to the direction of the exchange coupling magnetic field (that is, the direction of the applied magnetic field during the heat treatment), and Co (1 nm) / NiFe ( 5 nm), the direction of the magnetic field applied to the substrate was perpendicular to the exchange coupling magnetic field. Thereby, the direction of the exchange coupling magnetic field is orthogonal to the easy axis direction of the free layer. As a result of the above process, the overall structure of the present embodiment is: substrate / Ta (5 nm) / NiMn
(20 nm) / Co (3 nm) / Cu (2 nm) / Co
(1 nm) / NiFe (5 nm) / Ta (5 nm). As a result, the pinned layer is made of Co having a total thickness of 3 nm.

Comparative Example 1 A spin valve film having a conventional structure shown in FIG. 9 was manufactured as Comparative Example 1 for comparison with the spin valve film of Example 1. The multilayer structure of Comparative Example 1 is shown in FIG.
Has a structure in which the spin valve film of Example 1 shown in FIG. Comparative Example 1 was also manufactured using a dual ion beam sputtering apparatus. The film forming conditions and the like are the same as in Example 1, but in the case of Comparative Example 1, after the whole was continuously laminated in the same chamber, the film was heated at 250 ° C. × 6 in a vacuum heat treatment furnace.
Heat treatment was performed for a long time in a magnetic field. The direction of the applied magnetic field during the heat treatment is perpendicular to the direction of the applied magnetic field during film formation (the direction of the easy axis of the free layer). The magnitude of the exchange coupling magnetic field in Comparative Example 1 was 34 kA / m.

FIGS. 4 and 5 show magnetoresistive curves of Example 1 and Comparative Example 1, respectively. These magnetoresistance curves are obtained by measuring the change in electric resistance while applying an external magnetic field of 8 kA / m at the maximum in parallel with the exchange coupling magnetic field. In the figure, for convenience, the case where the external magnetic field is applied in the opposite direction to the exchange coupling magnetic field is positive, and the case where the external magnetic field is applied in parallel is negative. In Example 1, as in Comparative Example 1, the magnitude of the exchange coupling magnetic field is sufficiently larger than the maximum applied magnetic field of 8 kA / m, so that the magnetization direction of the pinned layer is firmly fixed in this case. Therefore, the resistance change rates shown in FIGS. 5 and 6 are due to the magnetization rotation of the free layer. As is clear from the comparison between FIGS. 5 and 6, the resistance change rate of Example 1 is higher than that of Comparative Example 1, and the magnetoresistive curve has a shape with small hysteresis and good linearity. Such an advantage is because, as described above, the multilayer portion of the pinned layer / nonmagnetic layer / free layer is not damaged by the heat treatment in the magnetic field. As described above, the magnetoresistive effect multilayer film of the present invention has higher performance than the conventional structure of FIG.

(Embodiment 2) In the prior art, the thickness of the NiMn layer is one of the factors affecting the rate of change in resistance.
Therefore, in order to clarify the relationship between the resistance change rate and the thickness of the NiMn layer in the present invention, a spin-valve film having the same multilayer structure as in Example 1 but having a varied NiMn layer thickness was manufactured as Example 2. The manufacturing method is the same as that in Example 1, except that the configuration of the laminated film formed in Step 1 is changed to the substrate / Ta (5
nm) / NiMn (x nm) / Co (3 nm) / Ta
(3 nm), the NiMn layer thickness x was used as a parameter.

(Comparative Example 2) A spin valve film having a multilayer structure similar to that of Example 1 but having a different NiMn layer thickness was produced as Comparative Example 2. The manufacturing method was the same as that of Example 1 except for the following points. That is, in Comparative Example 2, when the Ta and Co layers were removed by ion milling in Step 3 of Example 1, milling was performed until the NiMn layer was exposed.

FIG. 6 shows the dependency of the resistance change rate on the NiMn layer thickness in Example 2 and Comparative Example 2. The resistance change rate of Comparative Example 2 is smaller than that of Example 2 over the entire thickness of the NiMn layer. Thus, the performance is higher if the NiMn layer is not exposed during milling. Although the reason for this is not completely clear, the exchange coupling at the interface between the antiferromagnetic layer and the ferromagnetic layer is generally very sensitive to the state of the interface. It is considered that the exchange coupling magnetic field with the pin layer was impaired by irregularities generated by the milling and milling. In the present invention, such a problem does not occur because the NiMn layer is not exposed during milling. Furthermore, since the exchange coupling between the ferromagnetic layers is relatively insensitive to the state of the interface, exposing the pinned layer does not cause a problem in the exchange coupling.

Further, in Comparative Example 2 of the conventional method, the resistance change rate sharply decreases when the thickness of the NiMn layer becomes 20 nm or less, whereas in Example 2, even in a thin region where the thickness of the NiMn layer is about 15 nm, it is about 7%. It shows a high rate of resistance change. this is,
The result is that the electric resistance of the entire spin valve film is reduced and the shunt of the sense current to the NiMn layer is suppressed because the NiMn layer can be made thinner than before. The present invention also has such an effect.

(Embodiment 3) When the spin valve film is thinned, not only the resistance change rate is improved, but also the reproduction resolution of the MR head can be increased. So more NiM
In order to reduce the thickness of the n-layer, a C
A spin-valve film having a buffer layer made of u and having a thickness of 3 nm was prepared as Example 3. FIG. 7 shows a multilayer structure of the third embodiment. The fabrication method is the same as in Examples 1 and 2.

FIG. 6 shows the resistance change rate N in the third embodiment.
The iMn layer thickness dependence is also shown. As shown in the figure, in the case of Example 3, even if NiMn was thinned to 5 nm, the resistance change rate did not deteriorate, and a high resistance change rate of about 8% was obtained. The thickness of the entire spin valve film can be further reduced by 7 nm as compared with the second embodiment by providing a thin buffer layer. The reason is presumed as follows. In other words, the characteristics of the initial layer of the NiMn layer tend to deteriorate, but the presence of the interference layer makes the buffer layer a crystallographically uniform layer instead, and the initial layer of NiMn formed thereon has defects. It is presumed that the characteristics do not deteriorate.

Many transition metal elements other than Cu can be used for the buffer layer. Ti, V, Cr, Zr, Nb, Mo, Ru, P instead of Cu in the multilayer structure of the third embodiment
When d, Ir, Pt, and Au were used, a high resistance change rate of 7 to 8% was obtained for all elements even if the NiMn layer was as thin as 5 nm.

In Examples 1 to 3, Ni was used as the antiferromagnetic material.
Although the description has been made using the Mn alloy, the antiferromagnetic material to which the present invention can be applied is not limited thereto.
The same effect as described above can be obtained with a Mn type. Specifically, a binary alloy of PdMn and PtMn having a composition of about 50% Mn corresponds to this. A ternary alloy of NiPdMn, NiPtMn and PdPtMn having a composition of around 50% Mn also corresponds to this.
These alloys become antiferromagnetic when the crystal structure is a tetragonal CuAuI type ordered alloy and can generate a strong exchange coupling magnetic field, but are exactly the same as NiMn, which also requires heat treatment for ordered alloying. It is a material with features. Other features such as excellent corrosion resistance and heat resistance are not different from NiMn. Therefore, the present invention is effective even when any of these antiferromagnetic materials is used, and a magnetoresistance curve having a higher resistance change rate and excellent linearity can be obtained.

In Examples 1 to 3, the underlayer and the protective layer
Although the description has been made using a, Hf or an alloy thereof may be used. These metals become amorphous in a thin film state, and if they are used as an underlayer, they are effective in improving the crystallinity of the multilayer film. In addition, any of these metals reacts with oxygen to form a stable passivation layer, which is effective as a protective layer.

The film forming method is not limited to the ion beam sputtering method. DC magnetron sputtering and other suitable film forming methods can be used. In the present embodiment, the Ta and Co layers (part of) are removed by ion milling, but other methods such as RF etching can be used.

[0029]

According to the present invention, a NiMn type antiferromagnetic material which is excellent in magnetic properties, corrosion resistance and heat resistance but is difficult to be applied to a spin valve film due to the need for heat treatment is used. The present invention provides a multilayer structure applied to a semiconductor device and a method for manufacturing the same. The spin valve film according to the present invention is made of NiM.
The n-type antiferromagnetic material has both the high exchange coupling, corrosion resistance, and heat resistance inherently possessed by the n-type antiferromagnetic material, and has both a high resistance change rate and a linear, low-hysteresis magnetoresistance curve. A high rate of change in resistance improves the read output of the MR head, and a linear magnetoresistance curve makes the read waveform of the MR head symmetric and reduces noise. By adding a thinner buffer layer, the spin-valve film can be made thinner than before, so that the MR head using the spin-valve film according to the present invention can have a smaller gap length and better resolution.

[Brief description of the drawings]

FIG. 1 is a process chart showing a method for producing a magnetoresistive effect multilayer film according to the present invention.

FIG. 2 is a sectional view of a multilayer structure according to the present invention.

FIG. 3 is a cross-sectional view of a conventional multilayer structure.

FIG. 4 is a magnetoresistance curve of the magnetoresistance effect multilayer film according to the present invention.

FIG. 5 is a magnetoresistance curve of a conventional magnetoresistance effect multilayer film.

FIG. 6 is a graph showing a relationship between a rate of change in resistance and a thickness of a NiMn layer.

FIG. 7 is a cross-sectional view of a laminated structure according to another embodiment.

FIG. 8 is a perspective view of a recording / reproducing separation type head.

FIG. 9 is a sectional view showing the configuration of a conventional multilayer magnetoresistive film.

FIG. 10 shows a configuration of a conventional multilayer film.

[Explanation of symbols]

10 substrate, 11 antiferromagnetic layer, 12 ferromagnetic layer (pinned layer), 13 nonmagnetic layer, 14 ferromagnetic layer (free layer),
Reference Signs List 15 base layer, 16 protective layer, 17 buffer layer, 21 magnetoresistive effect film (MR film), 22 lower shield film, 23
Electrode, 24 upper shield film, 25 coil, 26 upper magnetic pole

Claims (5)

[Claims] The present invention has two or more ferromagnetic layers separated by a nonmagnetic layer, and one of the separated ferromagnetic layers receives an exchange coupling magnetic field from an adjacent antiferromagnetic layer. In the magnetoresistive multilayer film having a structure, after laminating a ferromagnetic layer on the antiferromagnetic layer, heat treatment is performed while applying a magnetic field,
Then, after removing a part of the ferromagnetic layer, a step of laminating a ferromagnetic layer to which an exchange coupling magnetic field is applied, a nonmagnetic layer, and a ferromagnetic layer to which no exchange coupling magnetic field is applied is provided. A method of manufacturing a magnetoresistive multilayer film. 2. The method according to claim 1, wherein a Mn—X alloy (X is at least one of Ni, Pd, and Pt) having a tetragonal structure is formed as the antiferromagnetic layer. A method of manufacturing a magnetoresistive effect multilayer film, comprising: 3. The method of manufacturing a magnetoresistive effect multilayer film according to claim 2, wherein Hf, T is formed below said antiferromagnetic layer.
a. A method for producing a magnetoresistive multilayer film, comprising the step of providing an underlayer made of a or an alloy thereof. 4. The method for manufacturing a magnetoresistive multilayer film according to claim 3, wherein the nonmagnetic transition metal has a cubic structure between the underlayer and the antiferromagnetic layer, or an alloy thereof. A method for manufacturing a magnetoresistive effect multilayer film, comprising a step of forming a buffer layer. 5. The method according to claim 3, further comprising the step of controlling the thickness of the antiferromagnetic layer to 20 nm or less. Method for producing effect multilayer film.